(1) Field of the Invention
The present invention generally relates to a power transmission belt. In particular, the present invention is directed to a power transmission belt having a reinforcement layer including an exterior fabric material that is a weft knitted structure with at least 2×2 ribs.
(2) Description of the Related Art
Many known power transmission belts include a body of belt material and a plurality of integrally formed teeth formed in the body along at least one surface of the belt. Known belts may also include a tensile member such as a steel cord embedded in the body as a load carrying member and a fabric material as reinforcement at the outside edge of the belt surface where the belt teeth are formed. One example of such a belt is a power transmission belt that is formed as a V-belt, i.e., a variable speed belt having teeth in the form of cogs, which define belt grooves to enhance the belt's flexibility. Another example of such a belt is a synchronous or timing belt where the teeth are designed to engage a toothed pulley to effect power transmission. The fabric material at the outside edge of the belt surfaces helps reinforce the teeth in every type of belt and enhances the overall wear resistance of the belt.
In using fabric material as reinforcement, it is desirable that the material have both a high heat resistance while at the same time having a structure that properly adheres to the body of the belt. It is also desirable to select a fabric material that sufficiently covers the body of the belt to minimize the amount of body material that is transferred to the surface of the transmission pulleys. U.S. Pat. No. 5,645,504, which is hereby incorporated by reference as if disclosed herein in its entirety, teaches a fabric material that is a weft knitted structure in the form of a 1×1 rib. A portion of the weft knitted structure is embedded in the body of the belt while another portion serves as an exterior surface covering for the belt teeth. The fabric material in U.S. Pat. No. 5,645,504 provides a material with a higher heat resistance and a structure that adheres to the body of the belt. However, weft knitted structures having a 1×1 rib may not sufficiently minimize the amount of body material that is transferred to the surface of the transmission pulleys.